tree f3b72c945f340d1f6e81ec124a8fb352d9de747f
parent 9d41c5bb07ad97b7777283d7922292f456ba4bfd
author Haiyang Zhang <haiyangz@microsoft.com> 1322855785 -0800
committer Greg Kroah-Hartman <gregkh@suse.de> 1323476810 -0800

net/hyperv: Fix the stop/wake queue mechanism

The ring buffer is only used to pass meta data for outbound packets. The
actual payload is accessed by DMA from the host. So the stop/wake queue
mechanism based on counting and comparing number of pages sent v.s. number
of pages in the ring buffer is wrong. Also, there is a race condition in
the stop/wake queue calls, which can stop xmit queue forever.

The new stop/wake queue mechanism is based on the actual bytes used by
outbound packets in the ring buffer. The check for number of outstanding
sends after stop queue prevents the race condition that can cause wake
queue happening earlier than stop queue.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reported-by: Long Li <longli@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>